The space available for the anterior cruciate ligament in the intercondylar notch is less in patients with ACL injury

A tight anterosuperior intercondylar notch may increase the risk of cyclops syndrome after anterior cruciate ligament reconstruction using a quadruple semi-tendinosus short autograft

BACKGROUND

Cyclops syndrome is loss of terminal knee extension caused by a fibrous nodule developed in the anterior intercondylar notch. The many known risk factors include preoperative motion-range limitation, tibial tunnel malposition, and tight hamstrings. The primary objective of this study was to assess whether intercondylar notch size was associated with the risk of cyclops syndrome or graft tear after anterior cruciate ligament (ACL) reconstruction using a quadruple semi-tendinosis autograft. The secondary objective was to determine whether intercondylar notch size was associated with functional outcomes.

HYPOTHESIS

A narrow intercondylar notch is associated with higher risks of cyclops syndrome and poor functional outcomes.

METHODS

Consecutive patients who underwent ACL reconstruction by quadruple semi-tendinosus autograft were included retrospectively. Preoperative magnetic resonance imaging scans were assessed by a single senior surgeon, who determined the conventional notch width index (NWI) and the anterior NWI (aNWI) for each patient.

RESULTS

The 120 included patients had a mean follow-up of 2.4±0.8 years. Among them, 20 (16.7%) experienced cyclops syndrome and 7 (5.8%) graft rupture. At last follow-up, 26 (21.7%) had not returned to sports and only 47 (39.2%) had returned to sports at the pre-injury level. The mean Lysholm score was 87.9±13.5 and the main subjective IKDC score was 84±13. A narrow notch was significantly associated with lower likelihoods of returning to sports (p=0.001), returning to the same sport (p<0.0001), and returning to the pre-injury sport level (p=0.004). By multivariate analysis, only the aNWI index was significantly associated with the risk of cyclops syndrome (p<0.0001). An aNWI index lower than 0.18 had 85% sensitivity and 78% specificity for predicting cyclops syndrome.

CONCLUSION

A narrow anterosuperior intercondylar notch may increase the risk of cyclops syndrome after ACL reconstruction using a quadruple semi-tendinosus graft but is not associated with the risk of graft rupture.

LEVEL OF EVIDENCE

IV, retrospective observational cohort study.

Tibial spine volume is smaller in ACL-injured athletes compared to healthy athletes

PURPOSE

The aim of this study was to investigate whether the whole tibial spine volume and femoral intercondylar notch volume are risk factors for anterior cruciate ligament (ACL) injury. The hypothesis was that the whole tibial spine volume and femoral notch volume would be smaller in athletes who sustained ACL injury than in athletes with no history of ACL injury.

METHODS

Computed tomography scans of both knees were acquired and three-dimensional bone models were created using Mimics to measure whole tibial spine volume and femoral notch volume. Tibial spine volume, femoral notch volume and each of these volumes normalised by tibial plateau area were compared between the ACL-injured and the ACL-intact group.

RESULTS

Fifty-one athletes undergoing unilateral anatomical ACL reconstruction (17 female, 34 male: average age 22.0 ± 7.5) and 19 healthy collegiate athletes with no previous knee injury (eight female, 11 male: average age 20.1 ± 1.3) were included in this study. The whole tibial spine volume in the ACL-injured group (2.1 ± 0.5 cm3) was 20.7% smaller than in the ACL-intact group (2.7 ± 0.7 cm3) (p = 0.005). No differences were observed between the femoral notch volume in the ACL-injured group (9.5 ± 2.1 cm3) and the ACL-intact group (8.7 ± 2.7 cm3) (n.s.).

CONCLUSIONS

The main finding of this study was that the whole tibial spine volume of the ACL-injured group was smaller than the ACL-intact group. A small tibial spine volume can be added to the list of anatomical risk factors that may predispose athletes to ACL injury.

LEVEL OF EVIDENCE

Level Ⅲ.

Body Mass Index Between 15 and 30 Does Not Influence Patient-Reported Outcomes After Anterior Cruciate Ligament Surgery Using a 10-mm-Diameter Bone-Tendon-Bone Graft

Purpose

To investigate the relation between body mass index (BMI) and outcomes after anterior cruciate ligament reconstruction (ACLR) using 10-mm-diameter bone-patellar tendon-bone grafts.

Methods

In this retrospective study, the Surgical Outcome System was used to measure patient-reported outcomes before and after ACLR between 2015 and 2019. The inclusion criteria consisted on patients undergoing primary ACLR performed by the senior surgeon, with recorded age of 15 years or older and BMI of 15.0 to 30. The exclusion criteria included revisions, concomitant procedures, age younger than 15 years, and unknown BMI. Patients were divided into cohorts to evaluate the Marx Activity Rating Scale (MARS), Tegner, International Knee Documentation Committee (IKDC), and Lysholm scores at various time points from injury to 2 years postoperatively.

Results

A total of 137 patients (100 male and 37 female patients) with an average age of 33 years (95% confidence interval, 30.6-35.4 years) and average BMI of 23.58 (95% confidence interval, 23.1-24.0) were divided into those with a BMI of 15 to 23.4 (group A, n = 69) and those with a BMI of 23.5 to 30 (group B, n = 68). A significant difference in MARS scores was found between the BMI groups before treatment, with mean scores of 11.55 (group A) and 9.41 (group B) (P = .011), and Tegner scores showed significance at 2 years, with scores of 6.45 and 5.41 for groups A and B, respectively (P = .009). Daily function scores were all insignificant. Female patients exhibited no significant differences across any patient-reported outcome measures or time points. Contrarily, male patients showed a significant difference in pretreatment MARS scores (14.30 in group A vs 9.96 in group B, P = .011). Additionally, scores at 2 years depicted Tegner values of 7.40 in group A versus 5.30 in group B (P = .012) and IKDC values of 96.92 in group A versus 90.47 in group B (P = .048). All results for female and male patients aged 30 years or younger indicated no significance.

Conclusions

Regardless of patient age or sex, BMI is not significantly associated with patient-reported outcomes after ACLR using 10-mm-diameter bone-patellar tendon-bone grafts.

Level of Evidence

Level III, retrospective cohort study.

Can the ACL Cross-Sectional Area Be Predicted? Size Correlation and Proportion between the ACL Cross-Sectional Area and the Femoral Intercondylar Notch Area

The purpose of this study was to reveal the correlation and proportion between the anterior cruciate ligament (ACL) cross-sectional area and the femoral intercondylar notch area. Sixty-three subjects (33 female and 30 male) less than 50 years old were included in this study. All subjects complained of knee pain, although magnetic resonance imaging (MRI) showed no structural damage of the knee. Using the T2 axial slice of the MRI perpendicular to the bone shaft, the ACL cross-sectional area and the femoral intercondylar notch area were measured. Measurements were made at the most proximal (S1), ⅓ (S2), ⅔ (S3), and the most distal (S4) Blumensaat's line levels. The correlation and the proportion between the ACL cross-sectional area and the notch area were calculated. The ACL cross-sectional area was: S1: 35.9 ± 10mm2, S2: 59.9 ± 14mm2, S3: 67.2 ± 19.5mm2, and S4: 70.7 ± 20.3mm2. The notch area was: S1: 215.5 ± 43mm2, S2: 311.8 ± 65mm2, S3: 453.8 ± 86mm2, and S4: 503.7 ± 99.8mm2. The ACL cross-sectional area and the notch area were found to be significantly correlated at the S3 (Pearson's coefficient correlation: 0.510, p = 0.000) and S4 (Pearson's coefficient correlation: 0.529, p = 0.000) levels. The proportion of the ACL cross-sectional area to the notch area was 15% in S3 and 14% in S4. The ACL cross-sectional area was found to be significantly correlated with the femoral intercondylar notch area at the distal level of the Blumensaat's line. The ACL cross-sectional area was found to be approximately 15% of the notch area. The ACL cross-sectional area can be predicted by measuring the femoral intercondylar notch area. This finding can be useful for achieving greater accuracy in anatomical ACL reconstruction. LEVEL OF EVIDENCE:  III.

The larger patellar tilt angle and lower intercondylar notch angle might increase posterior cruciate ligament injury risk: a retrospective comparative study

BACKGROUND

Posterior cruciate ligament (PCL) injuries are common ligament injuries of the knee, and previous studies often focused on the associations between the morphology of the knee and PCL injuries. Studies on the correlation between PCL injuries and patellofemoral alignment are limited.

METHODS

This retrospective study included 92 patients with PCL injured and 92 patients with PCL intact. Measurement parameters were compared between the two groups, including patellar tilt angle, congruence angle, patellar height, hip-knee-ankle angle, lateral trochlear inclination, femoral condyle ratio, bicondylar width, intercondylar notch width and index, notch angle, trochlear facet asymmetry, and trochlear sulcus depth and angle. Independent risk factors associated with PCL injuries were identified by logistic regression analyses.

RESULTS

In the PCL injured group, the patellar tilt angle was significantly larger (13.19 ± 5.90° vs. 10.02 ± 4.95°, P = 0.04); the intercondylar notch angle was significantly lower (60.97 ± 7.83° vs. 67.01 ± 6.00°, P = 0.004); the medial and lateral femoral condyle ratio were significantly larger (0.63 ± 0.64 vs. 0.60 ± 0.56, P = 0.031; 0.65 ± 0.60 vs. 0.58 ± 0.53, P = 0.005) than in the PCL intact group. There were 11 patients with patellar dislocation in the PCL injured group, accounting for 12%. In these patients, the patellar height was higher (1.39 ± 0.17 vs. 1.09 ± 0.25, P = 0.009); the trochlear sulcus angle was larger (157.70 ± 8.7° vs. 141.80 ± 8.78°, P < 0.001); and the trochlear sulcus depth was shallower (3.10 ± 1.20mm vs. 5.11 ± 1.48mm, P = 0.003) than those in the patients without patellar dislocation. Multivariate analyses showed that patellar tilt angle (each increase 1 degree, OR = 1.14) and intercondylar notch angle (each increase 1 degree, OR = 0.90) were independent risk factors for PCL injuries.

CONCLUSION

The patients with PCL injuries had larger patellar tilt angles, lower intercondylar notch angles, and longer posterior femoral condyles than patients with PCL intact. The larger patellar tilt angle and lower intercondylar notch angle might be risk factors for PCL injuries.

ACL Volume Measurement Using a Multi-truncated Pyramid Shape Simulation

Purpose

The purpose of this study was to measure anterior cruciate ligament (ACL) volume in a newly reported multi-truncated pyramid shape simulation using axial magnetic resonance imaging (MRI) for the detailed knowledge of the ACL anatomy.

Methods

Fifty subjects (27 female and 23 male, average age: 23 ± 7.8) visiting our clinic with knee pain and in whom MRI showed no structural injury were included in this study. Using the axial image of the MRI, four deferent levels of the cross-sectional area of the ACL were measured. ACL height was measured as the distance between the most proximal and distal slices of the MRI. ACL volume was calculated using a multi-truncated pyramid shape simulation. Femoral intercondylar notch height, area, and trans-epicondylar length (TEL) were also measured using MRI.

Results

The measured top, proximal 1/3, distal 1/3, and bottom of the ACL cross-sectional area were, 36.8 ± 10.7, 59.9 ± 15.4, 66.4 ± 20.8, and 107.3 ± 21.1mm2, respectively. ACL height was 26.3 ± 3.9 mm. Using these data, the calculated ACL volume was 1755 ± 874mm3. Significant correlations were observed between ACL volume and notch height, area, and TEL.

Conclusion

Similar ACL volume with previous reports was obtained in this simple and easy multi-truncated pyramid shape simulation from axial MRI evaluation. Significant correlation was observed between ACL volume and knee bony morphology. The ability of surgeons to measure ACL volume simply and effectively can be useful for the detailed ACL anatomical knowledge, and also for prediction and prevention of ACL injury.Level of evidence: IV, Case series.

Smaller intercondylar notch size and smaller ACL volume increase posterior cruciate ligament rupture risk

PURPOSE

Little is known about risk factors for sustaining a posterior cruciate ligament (PCL) rupture. Identifying risk factors is the first step in preventing a PCL rupture from occurring. The morphology of the knee in patients who ruptured their PCL may differ from that of control patients. The hypothesis was that the intercondylar notch dimensions, 3-D volumes of the intercondylar notch and, the 3-D volumes of both the ACL and the PCL were correlated to the presence of a PCL rupture.

METHODS

The magnetic resonance imaging (MRI) scans of 30 patients with a proven PCL rupture were compared to 30 matched control patients with proven intact ACL and PCL. Control patients were selected from patients with knee trauma during sports but without cruciate ligament injury. Patients have been matched for age, height, weight, BMI, and sex. The volumes of the intercondylar notch and both the ACL and PCL were measured on 3D reconstructions. Second, the bicondylar width, the notch width, and the notch width index were measured of all subjects. The relationship between our measurements and the presence of a PCL rupture was analysed.

RESULTS

The results show a significant difference in the volumes of the intercondylar notch and the ACL between patients with a ruptured PCL and control patients. Patients with a PCL rupture have smaller intercondylar notch volumes and smaller ACL volumes. There were no significant differences in the bicondylar width, notch width, and notch width index. In the control patients, a significant correlation between the volume of the PCL and the volume of the ACL was found (0.673, p < 0.001).

CONCLUSION

Patients with a PCL rupture have smaller intercondylar volumes and smaller ACL volumes when compared to control patients. Second, patients with smaller ACL volumes have smaller PCL volumes. This study shows, for the first time, that there are significant size and volume differences in the shape of the knee between patients with a PCL rupture and control patients.

LEVEL OF EVIDENCE

IV.

Does Femoral Intercondylar Notch Volume Differ in Anterior Cruciate Ligament-Injured Adult Patients Compared to the Uninjured?: A Meta-Analysis

BACKGROUND

Stenotic femoral intercondylar notch is considered as a risk factor for anterior cruciate ligament (ACL) injury and three-dimensional notch volume is used as a marker for the injury. The primary purpose of this study was to assess the difference in notch volume between the ACL-injured and uninjured in men and women combined or stratified by sex. The secondary purpose was to assess the difference in notch volume between the ACL-intact men and women.

METHODS

A search of PubMed/Medline, Scopus, Google Scholar, and Cochrane databases from inception to December 9, 2020, was conducted without restrictions using the following terms: ACL, notch, volume, notch volume, femoral notch volume, and intercondylar notch volume. Studies that compared the ACL-injured with uninjured controls were included. Independent extraction of articles by two authors using predefined data fields including study quality indicators was done. All pooled analyses were based on the inverse-variance weighted random effects model and mean difference was chosen as the effect measure.

RESULTS

Nine studies (1,169 knees) qualified for overall analysis (both sexes combined) and significant heterogeneity was observed, which disappeared after pooling studies with age-sex matched controls and those without. Notch volume in the ACL-injured was 0.75 cm3 (95% confidence interval [CI], 0.53-0.96 cm3), which was smaller than that in the age- and sex-matched controls. Six studies qualified for analysis in men. Notch volume in the ACL-injured men was smaller, especially when non-contact ACL injury was considered (1.40 cm3; 95% CI, 1.08-1.73 cm3). Five studies qualified for analysis in women and ACL-injured women had smaller notch volume irrespective of the mechanism of injury (0.38 cm3; 95% CI, 0.18-0.59 cm3). Notch volume of the uninjured men was larger than that of the uninjured women (1.86 cm3; 95% CI, 1.54-2.18 cm3).

CONCLUSIONS

ACL-injured adults have smaller notch volume than the age- and sex-matched controls. Non-contact ACL-injured males have smaller notch volume compared to ACL-intact males. ACL-injured females have smaller notch volume irrespective of the nature of injury. Men have higher notch volume than women. The quality of evidence is very low to low.

Quantifying graft impingement in anterior cruciate ligament reconstruction

BACKGROUND

Anterior cruciate ligament reconstructions (ACLR) fail at a rate of 10-15%, with graft impingement often a cause. In this study we investigate the prevalence and causes of impingement seen during ACLR surgery.

METHODS

We reviewed consecutive primary ACLR from 2012-2018. Graft impingement was estimated intraoperatively by placing the arthroscope through the tibial tunnel and passively extending the knee, observing how much was obscured by the lateral femoral condyle from an anterior and lateral direction. Preoperative MRI scans were used to measure the intercondylar notch; Notch Width Index (NWI) and Notch Depth Index (NDI). Positioning of the tunnels was determined on postoperative radiographs.

RESULTS

There were 283 ACLRs performed with 33 failures diagnosed on MRI (11.7%). 257 patients had complete imaging and follow up (91%). The mean age was 28 (±9) years and mean follow-up 5.3 (±1.8) years. The mean NWI was 0.26(±0.03), and NDI was 0.49(±0.06). The tibial tunnel aperture was located 42(±6) % of the way from anterior-posterior and 39(±6) % from medial-lateral. Impingement requiring a notchplasty was observed in 80% of cases, with lateral impingement more prominent.

CONCLUSIONS

The amount of impingement did not correlate with tunnel position, which was located within the recommended area. There was a weak negative correlation between NWI and lateral impingement (r_s = -0.16, p = 0.01), and NDI and anterior impingement (r_s = -0.12, p = 0.04), therefore a smaller notch is associated with greater impingement. Despite optimal tunnel positioning, impingement still occurs in a significant number of cases therefore notchplasty should always be considered to keep revision rates low.

Enlarged tibial eminence may be a protective factor of anterior cruciate ligament

Anterior cruciate ligament (ACL) is a primary stabilizer of the knee and constrains joint motion, and its injury is very common in clinic. There are many studies on the risk factors of ACL injury such as the ACL diameter, intercondylar notch width index (NWI), sagittal condylar shape, tibial posterior slope, tibia eminence size and so on. Large amount of research data has confirmed that all above are closely related to ACL injury. Among them the morphological characteristics of femoral condyle and tibial plateau are closely related to ACL injury. For example the tibial eminence, which is the hot topic of recent research. Whether or how does it relate to ACL injury has draw much interest of researchers. Since the tibial eminence and the ACL are both located in the intercondylar notch and adjacent to each other, we hypothesize the size of the tibial eminence may relate to the rupture of ACL. For there is report have found that reduced medial tibial eminence was associated with ACL injury, we suggest a hypothesis that enlarged tibia eminence may be a protective factor of ACL.